Abstract
We use large-eddy simulation (LES) to better define the early stages of the morning transition boundary layer. Previous LES studies relating to the morning transition boundary layer focus on the role of the entraining convective boundary layer (CBL). By using a combination of different domain sizes and grid lengths, the full evolution from the stable boundary layer (SBL) to the CBL is modelled here. In the early stages of the morning transition the boundary layer is shown to be a combination of a shallow mixed layer capped by a significant shear driven stable boundary layer (the so-called mixed CBL–SBL state). The mixed CBL–SBL state is the key to understanding the sensitivity to shear. Turbulent kinetic energy budgets also indicate that it is shear driven. The negative flux from the mixed CBL–SBL state extends much further above the minimum than is typically found for the CBL later in the day, and the depth of penetration scales as w m /N i , where w m is the combined friction and convective velocity scale and N i the static stability at the inversion top.
Similar content being viewed by others
References
Angevine WM, Baltink HK, Bosveld FC (2001) Observations of the morning transition of the convective boundary layer. Boundary-Layer Meteorol 101: 209–227
Beare RJ, MacVean MK (2004) Resolution sensitivity and scaling of large-eddy simulations of the stable boundary layer. Boundary-Layer Meteorol 112: 257–281
Beare RJ, Edwards JM, Lapworth AJ (2006a) Simulation of the observed evening transition and nocturnal boundary layers: large-eddy simulation. Q J Roy Meteorol Soc 132: 81–99
Beare RJ, MacVean MK, Holtslag AM, Cuxart J, Esau I, Golaz JC, Jimenez MA, Khairoutdinov M, Kosovic B, Lewellen D, Lund TS, Lundquist JK, McCabe A, Moene AF, Noh Y, Raasch S, Sullivan P (2006b) An intercomparison of large-eddy simulations of the stable boundary layer. Boundary-Layer Meteorol 118: 247–272
Clark TL, Farley RD (1984) Severe downslope windstorm calculations in two and three spatial dimensions using anelastic interactive grid nesting: a possible mechanism for gustiness. J Atmos Sci 41: 329–350
Lapworth A (2006) The morning transition of the nocturnal boundary layer. Boundary-Layer Meteorol 119: 501–526
Lock AP, Brown AR, Bush MR, Martin GM, Smith RNB (2000) A new boundary layer mixing scheme. Part I: scheme description and single-column model tests. Mon Wea Rev 128: 3187–3199
Moeng CH, Dudhia J, Klemp J, Sullivan P (2007) Examining two-way grid nesting for Large Eddy Simulation of the PBL using the WRF model. Mon Wea Rev 135: 2295–2311
Nieuwstadt FTM, Brost RA (1986) The decay of convective turbulence. J Atmos Sci 43: 532–546
Pino D, Jonker HJJ, de Arellano JVG, Dosio A (2006) Role of shear and the inversion strength during sunset turbulence over land: characteristic length scales. Boundary-Layer Meteorol 121: 537–556
Sorbjan Z (2007) A numerical study of daily transitions in the convective boundary layer. Boundary-Layer Meteorol 123: 365–383
Stull RB (1988) An introduction to boundary layer meteorology. Kluwer Academic, Dordrecht The Netherlands, pp 666
Sullivan PP, McWilliams JC, Moeng CH (1994) A subgrid-scale model for large-eddy simulation of planetary boundary-layer flows. Boundary-Layer Meteorol 71: 247–276
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Beare, R.J. The Role of Shear in the Morning Transition Boundary Layer. Boundary-Layer Meteorol 129, 395–410 (2008). https://doi.org/10.1007/s10546-008-9324-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10546-008-9324-8